The disclosure of the following priority application is herein incorporated by reference: Japanese Patent Application No. 2002-042643 filed Feb. 20, 2002
1. Field of the Invention
The present invention relates to a blur correcting device that corrects a blur occurring in a subject image and a lens barrel, used in an optical apparatus such as a camera.
2. Description of Related Art
Devices of this sort in the related art include those that correct an image blur by causing a blur correction optical system to shift within a plane substantially perpendicular to the optical axis of the optical system with an actuator such as a VCM (a voice coil motor).
Among such blur correcting devices in the known art, some are mounted with a locking device that holds the blur correction optical system at a specific position when its blur correcting function is not engaged.
For instance, Japanese Laid-Open Patent Publication No. H 08-211436 and Japanese Laid-Open Patent Publication No. H 08-87046 each disclose a locking mechanism achieved by utilizing a rotating ring-shaped member.
However, there are disadvantages to such a locking mechanism that utilizes a rotating ring-shaped member in that since the moment of inertia of the ring-shaped member is significant, the locking actuator must consume a great deal of power in order to execute a locking operation and a lock-releasing operation within a short period of time and in that the structure of the locking mechanism itself is bound to be complex and large.
In addition, Japanese Laid-Open Patent Publication No. H06-67274 proposes a locking mechanism which drives a pin with a latch solenoid.
FIGS. 7 and 8 present an example of a locking mechanism in the related art that drives a pin with a latch solenoid.
The locking mechanism in the related art comprises a locking pin 30, a locking spring 31, a locking lever 32 and a latch solenoid 33.
The locking pin 30, which is engaged with a casing member 8 at engaging portions 8a and 8b, is allowed to move along directions X1 and X2 running substantially parallel to an optical axis I in FIG. 7. The locking pin 30 includes a locking pin collar portion 30a, and a force is applied to the locking pin 30 by the locking spring 31 provided between the casing member 8 and the locking pin collar portion 30a in the direction X2, i.e., in the lock-releasing direction.
The latch solenoid 33 is fixed to the casing member 8, and a plunger 33a is allowed to move along the directions X1 and X2 when an electric current is supplied to the latch solenoid.
The locking lever 32 is mounted at the casing member 8 so as to be allowed to rotate freely around a rotational center 8g, with its one end 32b engaged with the locking pin collar portion 30a and the other end 32a engaged with the plunger 33a. 
During a locking operation, power is supplied to the latch solenoid 33 to pull the plunger 33a in the direction X2, which, in turn, causes the locking pin 30 to project out in the direction X1 via the locking lever 32. As a result, the locking pin 30 is driven into a locking hole 6f formed at a lens frame 6, and a blur correction lens 3 becomes held at a specific position.
During a lock-releasing operation, the force with which the plunger 33a is pulled in the direction X2 is weakened by supplying power to the latch solenoid 33 in a direction opposite from the direction in which power is supplied during the locking operation. Accordingly, the locking spring 31 causes the locking pin 30 to move in the direction X2, thereby releasing the lock on the blur correction lens 3.
However, while the locking mechanism that drives the pin with a latch solenoid enables the locking operation and lock-releasing operation to be executed within a very short period of time without requiring a great deal of power or a complex structure, there is a problem in that such a locking mechanism takes up considerable space and, in particular, requires a significant amount of space along the optical axis. There is an added concern in that the locking mechanism may restrict the movement of the optical system during zooming and focusing operations.
The present invention is to provide a blur correcting device, a lens barrel and the like, that allow a blur correction optical system to be locked and released very quickly with a high degree of reliability by adopting a simple structure that does not take up a great deal of space or require a great deal of power.
A blur correcting device according to the present invention comprises: a blur correction optical system that corrects an image blur by moving along a direction substantially perpendicular to an optical axis; a locking member that locks the blur correction optical system when an image blur correction is not executed; and a lock drive device having an elongated external shape with a length thereof set along a direction in which a tangential line of a circle having a center thereof at the optical axis extends on a plane substantially perpendicular to the optical axis, which generates a drive force to drive the locking member.
In this blur correcting device, it is preferable that the locking member locks the blur correction optical system by moving along the optical axis; the lock drive device generates the drive force along a direction in which the length thereof extends; and a transmitting member that transmits the drive force generated along the direction of the length of the lock drive device to the locking member by altering the direction to a direction in which the optical axis extends is also provided. In such a structure, it is preferable that the transmitting member is capable of rotating around a supporting point, and a triangle is formed by the supporting point, a point of application for the locking member and a point of application for the lock drive device. It is also preferable that a dimension of the lock drive device along a direction perpendicular to its lengthwise direction is smaller than a dimension of the locking member taken along the optical axis.
A lens barrel according to the present invention comprises a blur correcting device described above.
A photographing apparatus according to the present invention comprises a blur correcting device.
In another aspect of the lens barrel according to the present invention, the lens barrel comprises: a photographic optical system; a blur correction optical system constituting at least part of the photographic optical system, which corrects a blur by moving along a direction substantially perpendicular to an optical axis; a locking mechanism that locks the blur correction optical system when a blur correction operation is not executed; and a locking actuator having an elongated external shape with a length thereof set along a direction in which a tangential line of a circle having a center thereof at the optical axis extends on a plane substantially perpendicular to the optical axis, which generates a drive force to drive the locking mechanism.
It is preferable that this lens barrel further comprises: a blur correction actuator that drives the blur correction optical system; and a base member having an external circumference thereof formed as a substantially cylindrical surface, in which the blur correction actuator, the blur correction optical system, the locking mechanism and the locking actuator are provided, and that the locking actuator is a latch solenoid installed at a position at which the latch solenoid does not eclipse an effective optical path of the blur correction optical system and also the latch solenoid does not project out from the external circumference of the base member. In this case, it is preferable that the locking mechanism includes a locking pin that moves along a direction substantially parallel to the optical axis to become engaged with an engaging hole provided at the blur correction optical system; and a transmitting member that transmits the drive force imparted by the locking actuator to the locking pin; and that the transmitting member transmits the drive force from the locking actuator to the locking pin by altering a direction of the drive force.